Screw propeller



March 28, 1950 T, GOUDEN ET AL 2,501,720

SCREW PROPELLER Filed Nov. 24, 1944- Patented Mar. 28, 1950 SCREW PRorELLER Thomas Edward Godden, John Leslie Hunthold lishop,1 and Bernard Victor Holberton, Cheltenham, England, assignors to Rotol Limited, Gloucester, England, a British company Application November 24, 1944, serial No. 564,982

Great Britain December 24, 1943 Section 1, Public Law 690, August 8,' 1946 Patent expires December 24, 19.63`

' 201mm. (ci. 1ro-160.32)

`This invention relates to screw-propellers ,of the hydraulically-operated variable-pitch type andiis particularly, although not exclusively, suitable with propellers intended for marine propulsion.

In-such variable-pitch propellers the blades are-rotatably mounted in a small-diameter hub and pitch-changing movements are impartedr to the blades by` a hydraulic pitch-changing motor `comprisin'ga.piston sliding within aA cylinder which is formed'as a faired rearward extension of the hub. If the dimensions of the hub and cylinder are to be kept small, the problem arises of obtaining 'suiiicient power for effecting' pitchchanging" movements without using excessively high fluid-pressures, and an object of this invention is to provide a construction whereby this is achieved.

According to this invention, a pitch-changing inotor for a variable-pitch screw-propeller cornprises a'plurality of hydraulic rams having their movable elements connected in tandem and to the blades. Preferably the two rams are situated adjacent one another in an extension of the propeller-hub.

' According toanother feature of this invention, the pitch-changingmotor comprises two co-axial cylinders"separatedby va partition, a pistoncarrying element extending through said partition and carrying two pistons, one in each cylinder, and'means coupling them to theblades of thepropeller. The said piston-carrying element may Ibe'formed with a passage 'or passages providing communication between the cylinders on the sides of their pistons remote from the hub.

According to another feature of this'invention the said piston-carrying element is mountedto slide on a xed tubular member, which member provides communication from the interior of the hubto the cylinder remote from the hub on the nearer side of its piston. y

:According to another feature of this invention, the `piston which is more remote from vthe hub carriesa tube extending through said pistoncarrying element, and thehub into the driving shaft of the propeller for the supply of working fluid to the cylinders.'

The accompanying drawing isa longitudinal sectional view of a pitch-changing motor according to the present invention, applied to 4almarine propeller; i f 1 The hub of the propeller 4II) whereof one ofthe blades is shown at I I, has mounted upon its rear Wall I2 the usual form of streamlined boss I3 extending aft from it. but this boss is, in the present invention, hollow and forms two operating cylinders for a hydraulic pitch-changing motor. The boss I3 is preferably secured to the hub I0 by being screwed into a flange I4 thereof, and it is bored internally to yprovide two cylindersl5, I6, of which the cylinder I5 is somewhat smaller in diameter to be accommodated within the tapering outside formation of the boss.

Between the two cylinders there is provided` a partition I1 which constitutes the rear end Wall of the cylinder I6 and the forward end Wall of the cylinder I5. On the end Wall I2 of the hub, which is provided with a central aperture, there is mounted a bridge-piece I8 which carries, or has formed integrally with it, an extensionor fixed cylindrical member I9 which is splined on its outer surface at 20 to receive a correspondingly splined l piston-carrying element or sleeve 2l. The piston-carrying element or sleeve 2| carries a piston 22 at its forward end, reciprocable in the cylinder I6, and a piston 23 at its rear end, reciprocable in the cylinder I5 so that these two pistons are rigidly connected together in tandem. The piston 22 is connected by links 24, to the root end of each blade within the hub I0 for the purpose of effecting their pitch-changing movements. The links 24 are pivoted to knuckle members 25 which extend through openings 26 in the bridge-piece I8 aforesaid. f

The hub I0 is mounted by an adaptor 21,which is rotatable in the usual A-bracket 28 on the driving-shaft 29 for the propellenand pressureuid is supplied to the hydraulic cylinders I5, I6 in the following manner.

Upon vthe rear piston 23, there is mounted a tube 30 which extends forward through 'the piston-carrying element 2 I, throughthe hub and into the propeller-shaft 29; this tube vis conveniently made in sections screwed together to provide the necessary length, and one section of the tube at 34, adjacent the end of the propellershaft is splined thereto, so that when the pro'- peller and hub are removed, the portion of the tube 30 which it encloses is also Withdrawn and is not left projecting from the shaft. This -avoids possible damage to the tube and facilitates the assembly; also the splined tting of the part 34 prevents the various parts of the tubebecoming unscrewed from one another.

- The tube 30 extends into the propeller-shaft to a suitable point therein at which'communication is made with it by a running joint for the supply of'pressure-uid; as thetube 30 is mounted on rear piston 23 (as shown in the drawing) it will be reciprocated with movements of piston 3 23 and the running joint referred to also allows for such axial movements of the tube. A second running joint is provided on shaftl 2,9. The, annular space 4I between shaftl 2 9 and tube, 30 communicates, atone end, with one of the running joints referred to and, at the other end,.

with hub I0. The tube 30 is supported within shaft 29 by a bearing 4I having passagesl which allow pressure uid to flow past the bearing andl along space 40. The shaft 29ireceives4 anut, 42J

which is locked against rotation, in. well' known, manner, by a ring 43 which is toothed` to engage.

the splines 34 and has a lug 44 to enter a groove in the nut. within the groove by a spring clip 45. Thel ring- 43 has holes through it to allow the .annular space,

40 to communicate with the interior of hub I0.

The pressure iluid is controlled in conventional manner to pass either along tube 30ftoithehyv draulic cylinders I5, ISJ-at the same time the .annular space 4U and hub Illr are-connected to exhaust-or along space40fto the .interiorxof hub IIJ and thence both, throughl openings 26e-.to .cylf inders |16, and through an annular ypassage Mii-to cylinder IS-at thesametime the tube, 30;':is1connected` to exhaust.v The passage of pressulefl'uid to, and from, the tandem cylinders is "controlled in any convenien-t manner, either manuallyV or automatically 'as' may be desired .-such, mechanism beingI well known in connection `with variablepitch, airscrews.

The tube 3 0= does` .not communicate directly with cylinder- I6 but, as vwill be seen yin the drawingJ the tube opens Ato the rear. side =of pstongfZa-and communication is prov-ided therefrom -tocthe rear' vf sideof vpiston 22 by passages 32;; formed -in the pistonfcarrying element 2-I.and openings.

' Direct communication takes placefbetween the interior-of hub I0 and cylinder t6 ,through-fopen ings 26. The interior of the hub Illicommuniaites with cylinder I5 by passage -46 and radial ports 3-Il and 41. The latter is va fixed .size but-as :the piston, 23 movesrearwardly, takingl'tube 30,; Iwith it while member I9 remains stationary, the por-t 3| is elongated and communication between the passage 46 and the forward side Aof piston, 23 is thereby maintained throughout `the 4full,,stroke of said `piston in both directions. Normally; the pistons 22, 23 are more. centrally located in their cylinders than has been shown in theidrawing in'which case, for movements in ,onefdirectioni the port 3l is reduced in size to the minimum shown in the y,dra-wing and, .for movements inthe-:other direction, the port is enlarged.

Inthe operation of this mechanism, pitchchanging movementszof .the blades I I'of the propeller are effected in one direction by supplying pressure-fluid to the'interior .of the tube 30 and connecting the annularspace Varound it taeg-A haust. Pressure-fluid thereby vpasses, tothegrear sideof the piston 23 inthe cylinder t5 and thence to the rear side of the piston 22 inthe cylinder-H6 so that the piston is .moved forward. -Foradjustment ofA the pitch in the opposite-direction. the :interior of the tube30,isponnectedto drain and pressure-fluid is supplied .to xthe annular space around the tube 3Il'within, the .shaftiZ which communicates byy the interior .of theihub I0 and the passages 261 with the 4for-ward:side-lof thepiston 22, and by theinterior lof 1the splined tube I9 with the `forwardside .o f the lpiston'` 23 so that the pistonsare moved rearwardly.

.Itwill beseen that this .invention-,providesa The ring is held withvthe` lug 441 complete pitch-changing mechanism which is totally enclosed within the usual fairing of the propeller bossand in whichy the. eiectiye, pistonarea` is nearlydouble that which is available with the usual arrangement ofsingle hydraulic ram, so that ample power is rendered available for pitch-changing purposes without the use of exccssivelyl high fluid-pressures, and without the use ofl al1 undesirably large piston in the propeller boss.

Weclaim:

1; Flor use with a rotary propeller hub, the interior of which is selectively connectible with afsource of: active uid supply and with exhaust,

l and-angularly adjustable blades, a boss connected with; said hun and having an external taper .formed ,PlQgressiVely away from the hub, cylinders of differential diameters in said boss with the large rdiameter cylinder next the hub, a partition between said cylinders, pistons reciprocating in said cylinders, a piston-,carrying element 4rigidly lconnecting v said 4pistons and sl'idable through said partition, a tube extendlngthrough said-,element with one end selectively connectiblel with-a source of active uid supply and with exhaust-andthe other endopening to thesma'llend-iameter cylinder on the side of its piston away from'said'hub and-'a fixedv member having a cylindrical portion which surrounds andis spaced frorn'saiclv tube 'to forman inner annulary passage which placesythe smaller-diameter cylinder-on the-sideof its piston nearer to saidl hub in communication with the interior of the hub, said fixed member having aa hole for establishingAA communication between the larger diameter cylinder on the sidel ofj its` pistonnearer to the hub and the interior thereof and said cylindrical portion being nested Within, and spacedy from,y said piston-carrying element to form an outer annular passage which placesin communication the vsmaller andjlarger `clialllleter cylinders on the Side of their pistonsV awa-nimm said hub.

.2.' 'Ifhe combination of-claim l characterized'by the fact that the rear wall of the propeller ,hub provides means for detachably connecting the boss and also for detachably connecting abridgep'iece which carries 'the cylindrical poi-tiener, the, 'xed member.

THOMAS vCLOIDDEN.

JOHN LESHEHUNTHOID BISHOP.

BERNARD YIQKSI'QRA HOLBERTON.

REFERENCES CITED,

The: followingl referencesV are .of Athe lexofthis. patent:

` UNITED STATES 'PATENTS Certificate of Correction Patent No. 2,501,720 Merch 28, 1950 THOMAS EDWARD GODDEN ET AL.

It is hereby certified that errors appear in the above numbered patent requiring correction es follows:

In the grant, line 16, strike out December 24, 1968 and insert instead January 24, 1.963; in the heading to the printed specification, line 8, foreign filing date, for December 24, 1943 read January 24, 1.943; line 10, for December 24, 1963 read January 24, 1.963; and that the said Letters Patent should be read With these corrections therein that the seme may conform to the record of the cese in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

